Datasheet ILC6370BP-50, ILC6370BP-33, ILC6370BP-25, ILC6370AP-50, ILC6371CP-50 Datasheet (Impala Linear Corporation)

ILC 6370/71

SOT-89 Step up Switching Regulator with Shutdown

Impala Linear Cor poration

Impala Linear Corporation

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July 1999

ILC6370/1 1.3

50mA boost converter in 5-lead SOT-89 package. Only 3
external components are needed to complete the switcher
design, and frequency options of 50, 100, and 180kHz gives
the designer the ability to trade off system needs with
switcher design size.

87% max duty cycle gives conversion efficiencies of 85%.
Standard voltage options of 2.5V, 3.3V, and 5.0V at ±2.5%

accuracy feature on-chip phase compensation and soft­start design.

ILC6371 drives an external transistor for higher current
switcher design, with all of the features and benefits of
the ILC6370.

! 85% efficiency at 50mA
! Start-up voltages as low as 900mV
! ±2.5% accurate outputs
! Complete switcher design with only 3 external components
! 50, 100 and 180kHz switching frequency versions available
! Shutdown to 0.5µA
! External transistor option allows several hundred milliamp

switcher design

! Cellular Phones, Pagers
! Portable Cameras and Video Recorders
! Palmtops and PDAs

Ordering Information*

ILC6370CP-25

2.5V±2.5%@50kHz

ILC6370CP-25

3.3V±2.5%@50kHz

ILC6370CP-50

5.0V±2.5%@50kHz

ILC6370BP-25

2.5V±2.5%@100kHz

ILC6370BP-33

3.3V±2.5%@100kHz

ILC6370BP-50

5.0V±2.5%@100kHz

ILC6370AP-25

2.5V±2.5%@180kHz

ILC6370AP-33

3.3V±2.5%@180kHz

ILC6370AP-50

5.0V±2.5%@180kHz

ILC6371CP-25

2.5V±2.5%@50k Hz, ex ternal xtor

ILC6371CP-33

3.3V±2.5%@50k Hz, ex ternal xtor

ILC6371CP-50

5.0V±2.5%@50k Hz, ex ternal xtor

ILC6371BP-25

2.5V±2.5%@100k Hz , ex ternal xtor

ILC6371BP-33

3.3V±2.5%@100k Hz , ex ternal xtor

ILC6371BP-50

5.0V±2.5%@100k Hz , ex ternal xtor

ILC6371AP-25

2.5V±2.5%@180k Hz , ex ternal xtor

ILC6371AP-33

3.3V±2.5%@180k Hz , ex ternal xtor

ILC6371AP-50

5.0V±2.5%@180k Hz , ex ternal xtor

Standard Product offering comes in tape and reel,

quantity 1000 per reel, orientation right for SOT-89

VLX LIMITER

PWM Controlled

BUFFER

L

X

V

SS

EXT

+

-

CHIP ENABLE

OSC

50/100/180KHz

V

DD

V

OUT

CE

Phase comp

V

re f

Slow St art

VDD is internally connected to the V

OUT

pin.

SOT -89-5

(TOP VIEW)

132

V

OUT

CE

L

X

45

V

SS

N/C

SOT -89-5

(TOP VI EW )

132

V

OUT

CE

EXT

45

V

SS

N/C

ILC6370 ILC6371

General Description

Features

Applications

Block Diagram

Pin-Package Configurations

SOT-89 Step up Switching Regulator with Shutdown

Impala Linear Corporation

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ILC6370/1 1.3

Parameter

Symbol

Ratings

Units

V

OUT

Input Voltage Pin

V

OUT

12

V

CE Input Voltage

VCE

12

V

Voltage on pin LX

VLX

12

V

Current on pin LX

ILX

400

mA

Voltage on pin EXT

V

EXT

0.3 ~V

OUT

+0.3

V

Current pin EXT

I

EXT

+50

mA

Continuous Total Power Dissipation
(SOT-89-5)

PD

500

mW

Operating Ambient Temperature

T

OPR

-30~+80

οC

Storage Temperature

T

STG

-40~+125

οC

Parameter

Symbol

Conditions

Min

Typ

Max

Units

Output Voltage

V

OUT

3.218

3.300

3.383

V

Input Voltage

VIN 10

V

Oscillation Startup Voltage

V

ST2

LX :10kΩ Pull-up to.5V, V

OUT

= VST

500

600 mA

Operation Startup Voltage

V

ST1

I

OUT

+1mA

55

86

µA

Supply Current 1

IDD1

LX :10kΩ Pull-up to.5V, V

OUT

= 4.5V

1.5

2.5

µA

Supply Current 1

IDD2

Open Loop Measurement, V

S/D

= VIN,

VLX =V

IN-

0.4V, V

OUT

= 3V

0.64

0.85

Ω

L

X

Switch-On Resistance

R

SWON

Open Loop Measurement, V

OUT

= V

IN,

V

LX

= 0V

2.0

µA

L

X

Leakage Current

ILXL

Measure Waveform at EXT pin V

IN

= 3.6V

I

OUT

= 20mA

255

300

345

KHz

Oscillator Frequency

F

OSC

100 %

Maximum Duty Ratio

MAXDTY

No Load

10

17

25

%

Satndb-by Current

I

STB

95 %

CE "High " Voltage

V

CEH

Minimum V

IN

When V

ref

does not start up

1 1.8

V

CE "Low " Voltage

V

CEL

V

ref

rises to 0V from 0.9V

6.0

10.0

16.0

msec

Note: Unless otherwise spcified, VIN= V

OUT

x 0.6, I

OUT

= 50mA. See Schematic, figure 1.

Absolute Maximum Ratings (TA = 25°C)

V

OUT

= 5.0V, F

OSC

= 100kHz, TA= 25°C, Test Circuit of figure 1

Elcetrical Characteristics ILC6370BP-50

SOT-89 Step up Switching Regulator with Shutdown

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ILC6370/1 1.3

Parameter

Symbol

Conditions

Min

Typ

Max

Units

CE “High” Current

I

CEH

LX: 10kΩ pull-up to 5V, V

CE

= V

OUT

= 4.5V

0.25

µA

CE “Low” Current

I

CEL

LX: 10kΩ pull-up to 5V, V

OUT

=

4.5V, VCE = 0V

-0.25

µ

LX Limit Voltage

V

LXLMT

LX: 10kΩ pull-up to 5V, V

OUT

= 4.5V, F

OSC

> F

OSC

x 2

(1)

0.7 1.1

V

Efficie ncy

EFFI

85 %

Parameter

Symbol

Conditions

Min

Typ

Max

Units

Output Voltage

V

OUT

4.875 5.000

5.125

V
Input Voltage

V

IN

10

V
Oscillation Startup Voltage

V

ST

EXT: 10kΩ pull-up to 5V, V

OUT

= V

ST

0.8

V
Supply Current 1

IDD 1

EXT: 10kΩ pull-up to 5V, V

OUT

= 4.5V

38.4

64.1

µA
Supply Current 2

IDD 2

EXT: 10kΩ pull-up to 5V, V

OUT

= 5.5V

6.9

13.8

µA
EXT “High” On-Resistance

R

EXTH

EXT: 10kΩ pull-up to 5V, V

OUT

= 4.5V,

V

EXT

= 4.1V

30

50

Ω

EXT “Low” On-Resistance

R

EXTL

V

EXT

= 0.4V, V

OUT

= 5.5V

30

50

Ω

Oscillator Frequency

F

OSC

EXT: 10kΩ pull-up to 5V, V

OUT

= 4.5V,

Measuring of EXT pin

85

100

115

kHz
Maximum Duty Ratio

MAXDTY

EXT: 10kΩ pull-up to 5V, V

OUT

= 4.5V,

Measuring of EXT pin

80

87

92

%
Stand-by Current

I

STB

EXT: 10kΩ pull-up to 5V, V

OUT

= 4.5V

0.5

µA
CE “High” Voltage

V

CEH

EXT: 10kΩ pull-up to 5V, V

OUT

= 4.5V,

Existance of L

X

Oscillation

0.75

V
CE “Low” Voltage

V

CEL

EXT: 10kΩ pull-up to 5V, V

OUT

= 4.5V,

Stopped L

X

Oscillation

0.20

V
CE “High” Current

I

CEH

EXT: 10kΩ pull-up to 5V, V

OUT

= VCE = 4.5V

0.25

µA
CE “Low” Current

I

CEL

EXT: 10kΩ pull-up to 5V, V

OUT

= 4.5V, VCE = 0V

-0.25

µA
Efficiency

EFFI

85 %
Slow Start Time

T

SS

10 msec

V

OUT

= 5.0V, F

OSC

= 100kHz, TA= 25°C; Test Circuit of figure 1

1. Switching frequency determined by delay time of internal comparator to turn LX“OFF,” and minimum “ON” time as
determined by MAXDTY spec.

V

OUT

= 5.0V, F

OSC

= 100kHz, TA= 25°C; Test Curcuit of figure 2.

Electrical Characteristics ILC6370BP-50

Electrical Characteristics ILC6371BP-50

SOT-89 Step up Switching Regulator with Shutdown

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ILC6370/1 1.3

Parameter

Slow Start Time

Symbol

T

SS

Conditons Min Typ

10

Max Units

msec

V

OUT

= 5.0V, F

OSC

= 100kHz, TA= 25°C; Test Circuit of figure 1

ILC6370

123

45

CE
V

OUT

C

L

+

GND

V

IN

L

SD

ILC6371

123

45

CE
V

OUT

C

L

+

L

SD

V

IN

GND

C

B

R

B

Tr

L: 100µH (SUMIDA, CD-54)
SD: Diode (Schottky diode; MATSUSHITA MA735)
CL: 16V 47µF (Tantalum Capacitor; NICHICON, F93)

L: 100µH (SUMIDA, CD-54)
SD: Diode (Schottky diode; MATSUSHITA MA735)
CL: 16V 47µF (Tantalum Capacitor; NICHICON, F93)

R

B

: 1kΩ

C

B

: 3300pF

Tr: 2SC3279, 2SDI628G

Figure 1: Test Circuit

Figure 2: Test Circuit

Applications Circuits

Electrical Characteristics ILC6370BP-50

SOT-89 Step up Switching Regulator with Shutdown

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ILC6370/1 1.3

The ILC6370 performs boost DC-DC conversion by controlling the
switch element shown in the circuit below.

When the switch is closed, current is built up through the inductor.
When the switch opens, this current has to go somewhere and is
forced through the diode to the output. As this on and off switch­ing continues, the output capacitor voltage builds up due to the
charge it is storing from the inductor current. In this way, the out­put voltage gets boosted relative to the input. The ILC6370 mon­itors the voltage on the output capacitor to determine how much
and how often to drive the switch.

In general, the switching characteristic is determined by the output
voltage desired and the current required by the load. Specifically
the energy transfer is determined by the power stored in the coil
during each switching cycle.

PL = ƒ(t

ON

, VIN)

The ILC6370 and ILC6371 use a PWM or Pulse Width Modulation
technique. The parts come in one of three fixed internal frequen­cies: 50, 100, or 180kHz. The switches are constantly driven at
these frequencies. The control circuitry varies the power being
delivered to the load by varying the on-time, or duty cycle, of the
switch. Since more on-time translates to higher current build up in
the inductor, the maxmim duty cycle of the switch determines the
maximum load current that the device can support. The ILC6370
and ILC6371 both support up to 87% duty cycles, for maximum
usable range of load currents.

There are two key advantages of PWM type controllers. First,
because the controller automatically varies the duty cycle of the
switche’s on-time in response to changing load conditions, the
PWM controller will always have an optimized waveform for a
steady-state load. This translates to very good efficiency at high
currents and minimal ripple on the output. [Ripple is due to the

output cap constanty accepting and storing the charge recieved
from the inductor, and delivering charge as required by the load.
The “pumping” action of the switch produces a sawtooth-shaped
voltage as seen by the output.]

The other key advatage of the PWM type controllers is that the
radiated noise due to the swtiching transients will always occur at
the (fixed) switching frequency. Many applications do not care
much about switching noise, but certain types of applications,
especially communication equipment, need to minimze the high
frequency interference within their system as much as is possible.
Using a boost converter requires a certain amount of higher fre­quency noise to be generated; using a PWM converter makes that
noise highly predictable; thus easier to filter out.

There are downsides of PWM approaches, especially at very low
currents. Because the PWM technique relies on constant switch­ing and varying duty cycle to match the load conditions, there is

some point where the load current gets to small to be handled effi­ciently. If the ILC6370 had an ideal switch, this would not be such
a problem. But an actual switch consumes some finite amount of
current to switch on and off; at very low current this can be of the
same magnitude as the load current itself, driving switching effi­ciencies down to 50% and below.

The other limitation of PWM techniques is that, while the funda­mental switching frequency is easier to filter out since it’s constant,
the higher order harmonics of PWM will be present and may have
to be filtered out as well. Any filtering rquirements will vary by appli­cation and by actual system design and layout, so generalizations
in this area are difficult, at best. [For other boost converter tech-
niques, please see the ILC6380/81 and ILC6390/91 data sheets.]

However, PWM control for boost DC-DC conversion is widely
used, especially in audio-noise sensitive applications or applica­tions requiring strict filtering of the high frequency components.
Impala’s products give very good efficiencies of 85% at 50mA out­put (5V operation), 87% maximum duty cycles for high load con­ditions, while maintaining very low shutdown current levels of

0.5µA. The only difference between the ILC6370 and ILC6371
parts is that the 6371 is configured to drive an external transistor
as the switch element. Since larger transistors can be selected for
this element, higher effective loads can be regulated.

Start-up Mode

The ILC6370 has an internal soft-start mode which suppresses
ringing or overshoot on the output during start-up. The following
diagram illustrates this start-up condition’s typical performance

External Components and Layout Consideration

The ILC6370 is designed to provide a complete DC-DC convertor
solution with a minmum of external components. Ideally, only
three externals are required: the inductor, a pass diode, and an
output capacitor.

The inductor needs to be of low DC Resistance type, typically 1Ω
value. T oroidal wound inductors have better field containment (less
high frequency noise radiated out) but tend to be more expensive.
Some manufacturers like Coilcraft have new bobbin-wound induc­tors with shielding included, which may be an ideal fit for these
applications. Contact the manufacturer for more information.

The inductor size needs to be in the range of 47µH to 1mH. In
general, larger inductor sizes deliver less current, so the load cur­rent wil determine the inductor size used.

VIN - V

f

V

OUT MIN

T

SOFT-START

(~10msec)

t = 0

Functions and Operation

SOT-89 Step up Switching Regulator with Shutdown

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ILC6370/1 1.3

For load currents higher than 10mA, use an inductor from 47µH to
100µH. [The 100µH inductor shown in the data sheet is the most
typical used for this application.]

For load currents of around 5mA, such as pagers, use an indcutor
in the range of 100µH to 330µH. 220µH is the most typical value
used here.

For lighter loads, an inductor of up to 1mH can be used. The use
of a larger inductor will increase overall conversion efficiency, due
to the reduction in switching currents through the device.

For the ILC6371, using an external transistor, the use of a 47µH
inductor is recommended based on our experience with the part.
Note that these values are recommended for both 50kHz and
100kHz operation. If using the ILC6370 or ILC6371 at 180kHz,
the inductor size can be reduced to approximately half of these
stated values.

The capacitor should, in general, always be tantalum type, as tan­talum has much better ESR and temperature stability than other
capacitor types. NEVER use electrolytics or chemical caps, as the
C-value changes below 0°C so much as to make the overall
design unstable.

Different C-values will directly impact the ripple seen on the output
at a given load current, due to the direct charge-to-voltage rela­tionship of this element. Different C-Values will also indirectly
affect system reliability, as the lifetime of the capacitor can be
degraded by constant high current influx and outflux. Running a
capacitor near its maximum rated voltage can deteriorate lifetime
as well; this is especially true for tantalum caps which are particu­larly sensitive to overvoltage conditions.

In general, this capacitor should always be 47µF, Tantalum,
16V rating.

The diode must be of shottkey type for fast recovery and minimal
loss. A diode rated at greater than 200mA and maximum voltage
greater than 30V is recommended for the fastest switching time
and best reliability over time. Different diodes may introduce dif­ferent level of high frequency switching noise into the output
waveform, so trying out several sources may make the most
sense for your system.

For the ILC6371, much of the component selection is as described
above, with the addition of the external NPN transistor and the
base drive network. The transistor needs to be of NPN type, and
shoud be rated for currents of 2A or more. [This translates to

lower effective on resistance and, therefore, higher overall effi­ciencies.] The base components should remain at 1kΩ and

3300kΩ; any changes need to be verified prior to implementation.
As for actual physical component layout, in general, the more

compact the layout is, the better the overall performance will be. It
is important to remember that everything in the circuit depends on
a common and solid ground reference. Ground bounce can direct­ly affect the output regulation and presents difficult behavior to
predict. Keeping all ground traces wide will elliminate ground
bounce problems.

It is also critical that the ground pin of C

L

and VSSpin of the

device be the same pin on the board, as this capacitor serves two
functions: that of the output load capacitor, and that of the input
supply bypass capacitor.

Layouts for DC-DC converter designs are critical for overall
performance, but following these simple guidlines can simplify
the task by avoiding some of the more common mistakes made
in these cases. Once actual performance is completed, be
sure to double check the design on an actual manufacturing
prototype prodcut to verfy that nothing has changed which can
affect the performance.

SOT-89 Step up Switching Regulator with Shutdown

OUTPUT VOLTAGE vs. OUTPUT CURRENT OUTPUT VOLTAGE vs. OUTPUT CURRENT

ILC6370CP-50

ILC6370CP-50

ILC6370CP-50

ILC6370CP-50, No Load Current ILC6370CP-30, No Load Current

ILC6370CP-30

ILC6370CP-30

ILC6370CP-30

5.4

5.2

5.0

4.8

4.6

4.4

4.4

4.0

5.4

5.2

5.0

4.8

4.6

4.4

4.4

4.0

0 100 200 300 400 500

0 40 80 120 160 200

OUTPUT CURRENT I

OUT

(mA)

OUTPUT VOLTAGE V

OUT

(v)

OUTPUT VOLTAGE V

OUT

(v)

VIN= 2.0V

VIN= 2.0V

VIN= 2.0V

VIN= 3.0V

VIN= 3.0V

VIN= 3.0V

VIN= 4.0V

VIN= 4.0V

VIN= 4.0V

VIN= 1.0V

VIN= 1.0V

VIN= 1.0V

VIN= 1.5V

VIN= 1.5V

VIN= 1.5V

VIN= 2.0V

VIN= 2.0V

VIN= 2.0V

VIN= 1.0V

VIN= 1.0V

VIN= .9V

L = 100µH
C = 47µF (Tantalum)

L = 100µH
C = 47µF (Tantalum)

L = 100µH
C = 47µF (Tantalum)

L = 100µH
C = 47µF (Tantalum)

L = 100µH
C = 47µF (Tantalum)

L = 100µH
C = 47µF (Tantalum)

OUTPUT CURRENT I

OUT

(mA)

0 100 200 300 400 500

OUTPUT CURRENT I

OUT

(mA)

100

80

60

40

20

0

EFFICIENCY vs. OUTPUT CURRENT

EFFICIENCY vs. OUTPUT CURRENT

EFFICIENCY: EFFI (%)

EFFICIENCY: EFFI (%)

100

80

60

40

20

0

OUTPUT CURRENT I

OUT

(mA)

0 40 80 120 160 200

OUTPUT CURRENT I

OUT

(mA)

100

80

60

40

20

0

0 50 100 150 200

RIPPLE VOLTAGE vs. OUTPUT CURRENT

RIPPLE VOLTAGE vs. OUTPUT CURRENT

RIPPLE Vr (mV p-p)

100

80

60

40

20

0

0 100 200 300 400 500

OUTPUT CURRENT I

OUT

(mA)

RIPPLE Vr (mV p-p)

INPUT VOLTAGE vs. OUTPUT CURRENT

INPUT VOLTAGE vs. OUTPUT CURRENT

100

500

400

300

200

100

0

1 2 3 4

INPUT VOLTAGE VIN(V)

INPUT CURRENT (µA)

L = 100µH
RL= 0
C = 47µF (Tantalum)

L = 100µH
RL= 0
C = 47µF (Tantalum)

INPUT VOLTAGE VIN(V)

250

200

150

100

50

0

1.0 1.2 1.4 1.6 1.8 2.0

INPUT CURRENT (µA)

Typical Performance Characteristics General conditions for all curves

ILC6370/1 1.3

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SOT-89 Step up Switching Regulator with Shutdown

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ILC6370/1 1.3

START VOLTAGE/HOLD VOLTAGE vs. I

OUT

ILC6370CP-50

ILC6370CP-50

V

ST,

V

HLD

(

ςς

)

1.2

1.0

0.8

0.6

0.4

0.2

0

OUTPUT CURRENT I

OUT

(mA)

010 20 30

L = 100µH
C = 47µF (Tantalum)

V

HLD

V

ST

TRANSIENT RESPONSE

7.0

6.0

5.0

4.0

3.0

-20 0 20 40 60 80

VIN= 3.0V
I

OUT

= 1mA~30mA

L = 100µH
C = 47µF (Tantallum)

TIME (µsec)

OUTPUT VOLTAGE V

OUT

(V)

Typical Performance Characteristics General conditions for all curves